The main keep was rebuilt in 1958, a replica of the original that now serves as a museum of Hiroshima's history before World War II, and other castle buildings have been reconstructed since.

After the Meiji Restoration, the castle came to serve as a military facility, and the Imperial General Headquarters was based there during the First Sino-Japanese War in 1894–1895.

During the final months of World War II, the castle served as the headquarters of the 2nd General Army and Fifth Division, stationed there to deter the projected Allied invasion of the Japanese mainland.

The castle buildings were originally constructed in wood, pine primarily, and the main keep had attached wings to the east and to the south.

The two outer moats were filled in during the late 19th and early 20th centuries, and much of what was once within the castle grounds is now modern urban area, including homes, schools, offices and shops.

A number of secondary castle buildings, towers and turrets once stood, and a Shinto shrine called Hiroshima Gokoku Jinja is located within the innermost moat, having been moved there after 1945.

Also located inside the Honmaru is the concrete bunker from which the first radio broadcast out of Hiroshima following the atomic bombing was made.